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9Sci CH7
9th Science CH7 Machines-Making Work Easier
| Term | Definition |
|---|---|
| bionics | the science of designing artificial replacements (prostheses) for parts of the human body that are not working properly |
| compound machine | a combination of two or more simple machines |
| efficiency | the ratio of the useful work put out by a machine to the work put into that machine; efficiency is always less than 100 percent |
| effort arm | the part of a lever on which an effort force is applied |
| effort force | the force applied to a machine, when a machine is used to do work |
| fulcrum | the fixed point around which a lever pivots |
| ideal machine | a machine in which work input equals work output; such a “perfect” machine would be friction-less and 100 percent efficient |
| inclined plane | a simple machine consisting of a sloping surface (ramp) used to raise objects |
| lever | a simple machine consisting of a bar that is free to pivot (rotate) around a fixed point (fulcrum) |
| machine | a device that makes work easier by changing the size of the force applied to it and/or the direction of that force |
| mechanical advantage | the number of times a machine multiplies the effort force applied to it |
| power | the measure of the amount of work done in a specific amount of time; power is measured in watts and equals 1 joule/second |
| pulley | a simple machine consisting of a grooved wheel with a rope or chain running along the groove |
| resistance arm | the part of a lever that exerts the resistance force |
| resistance force | the force exerted by a machine to overcome resistance to gravity or friction |
| screw | a simple machine consisting of a special type of inclined plane wrapped in a spiral around a cylindrical post |
| simple machine | a device that accomplishes work with only one movement; the lever, pulley, wheel and axle, inclined plane, screw,and wedge are all simple machines |
| wedge | a simple machine consisting of a moving inclined plane with one or two sloping sides; examples are knives and chisels |
| wheel and axle | a simple machine consisting of two different-sized wheels that rotate together, such as a doorknob |
Created by:
djhockett5
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